Preparation and Optical Properties of Zirconium–Titanium–Oxide Thin Films by Reactive Sputtering

概要

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Zirconium–titanium–oxide thin films were prepared by multi-target rf reactive sputtering using metallic targets of zirconium and titanium. The compositional ratio of zirconium to titanium in the thin films was precisely controlled through rf power. Zirconium and titanium in the thin films were found to exist as mixtures of chemically bonded ZrO2 and TiO2 from XPS spectra. The zirconium–titanium–oxide thin films with compositional ratio $x<0.42$ were identified to have a tetragonal crystal structure, whereas those with $x\geqq 0.42$ were identified to be in the amorphous state. The refractive index of the zirconium–titanium–oxide thin film at a wavelength of 550 nm changed from 2.25 to 2.55 according to compositional ratio $x$, and the dispersion of the refractive index was analyzed using the Lorentz oscillator model with four oscillators. It was clarified that the estimated oscillator energies $E_{1}$ (10.5 eV) and $E_{2}$ (6.5 eV) correspond to zirconium oxide, and that $E_{3}$ (5.5 eV) and $E_{4}$ (4.3 eV) correspond to titanium oxide from fundamental absorption spectra and photoconductivity.
Published by the Japan Society of Applied Physics through the Institute of Pure and Applied Physicsの論文
2005-02-15